Up to now, as a fuel supply system for an internal combustion engine such as a gasoline engine or a diesel engine, an in-cylinder injection fuel supply system that includes a high-pressure pump that pressurizes a low-pressure fuel pumped up from a fuel tank and a pressure accumulation pipe that accumulates a high-pressure fuel pumped from the high-pressure pump, and injects the high-pressure fuel in the pressure accumulation pipe directly into cylinders of the internal combustion engine from respective fuel injection valves has been known. An example of the high-pressure pump that includes a plunger that reciprocates in each cylinder, a pressurizing chamber into which the fuel is introduced from a low-pressure side, and an electromagnetic drive control valve that regulates a return amount of the fuel introduced into the pressurizing chamber has been known.
As an example of the high-pressure pump, the plunger is connected to a rotating shaft of an output shaft (crankshaft) of the internal combustion engine. The plunger reciprocates in the cylinder while the rotating shaft rotates with the rotation of the crankshaft, and varies a volume of the pressurizing chamber. The control valve is configured by, for example, a normally open electromagnetic valve, and during deenergization of the solenoid coil, a valve body is held at a valve open position due to a spring to allow an introduction of the fuel into the pressurizing chamber from a low-pressure side passage. On the other hand, during the energization of the coil, the valve body is displaced to a valve closing position due to an electromagnetic force to cut off the introduction of the fuel into the pressurizing chamber. In a state where the valve body of the control valve is located at the valve open position in a volume reduction stroke of the pressurizing chamber, a surplus fuel is returned to the low-pressure side from the pressurizing chamber with the movement of the plunger. Thereafter, when the valve body is moved to the valve closing position with the energization of the coil under control, the fuel in the pressurizing chamber is pressurized by the plunger and discharged toward a high pressure side. With the above operation, a discharge amount control of the high-pressure pump is performed.
In the operation of the control valve, a collision noise is generated when the valve body collides with a movement restriction member (stopper), and may bring discomfort to an occupant of the vehicle. Under the circumstance, up to now, in a discharge amount control of the high-pressure pump by the aid of the control valve, various methods for reducing the collision noise between the valve body and the stopper have been proposed (for example, refer to Patent Literature 1). Patent Literature 1 discloses that a current value in energizing the control valve to close the control valve is set to a valve closeable minimum value to decrease a moving speed of the valve body, as a result of which the collision noise when the valve body collides with the stopper is reduced.